Accessing Point Data of an Animated Bezier Curve Through Python API
Could you perhaps solve your problem by using Hooks?


Edit the curve
select the endpoint you want controlled by the empty.
Ctrl-h and Hook to New Object


Now moving the freshly-created empty drags the curve control point around.

It is also possible to hook the control points to bones in an armature, or maybe just select the hand and the curve and hook the control point to the hand object.